Most people know the herpes virus from cold sores on the lip. It is less well known that the same virus can also attack the eye – and that it is one of the leading infectious causes of corneal scarring in the Western world. What makes eye herpes distinctive is that it recurs: the virus “sleeps” in a nerve and wakes up from time to time, and each recurrence can add further damage. That is why accurate diagnosis, precise treatment and preventing attacks are the key to preserving vision over the years.
What is eye herpes
Eye herpes (Herpes Simplex Keratitis) is caused by the herpes simplex virus, usually the same type that causes cold sores. After the first infection, which usually happens in childhood and passes unnoticed, the virus stays dormant in the ganglion of a facial nerve. From time to time – sometimes after a feverish illness, strong sun exposure, stress, or for no known reason – it reactivates and travels along the nerve to the eye.
The disease takes several forms, depending on which layer is affected:
- Epithelial herpes – the most common form. The virus itself damages the surface layer of the cornea and creates a branching ulcer (a “dendrite”) that shows up clearly with staining.
- Stromal herpes – affecting the thick layer of the cornea. Here the damage is caused mainly by the immune system’s inflammatory reaction to the virus, and it is this that can leave scars, blood vessels in the cornea and reduced vision.
- Endotheliitis – inflammation of the inner layer; it causes swelling and clouding of the cornea.
- Involvement of the eyelid, the conjunctiva and sometimes the inside of the eye as well (uveitis).
Symptoms
- Redness, usually in one eye only.
- Pain or a foreign body sensation, sensitivity to light and watering.
- Blurred vision.
- Sometimes blisters on the eyelid or around the eye.
- Over time: reduced sensation in the cornea – which is why the pain is sometimes mild compared with what is seen on examination.
Because the symptoms resemble simple conjunctivitis, it is not unusual for herpes to be diagnosed late. A red eye on one side that does not go away, especially in someone who has had eye herpes before, needs a slit-lamp examination (see also conjunctivitis).
How it is diagnosed
The diagnosis is mainly clinical: on slit-lamp examination with staining, each form of the disease has a characteristic appearance. The doctor also checks corneal sensation, eye pressure and the inside of the eye. In unclear cases a sample can be taken for a PCR test to identify the virus.
Treatment
In epithelial herpes an antiviral medication is given – a gel or drops for the eye, or tablets. Sometimes the doctor also gently removes the infected cells. Steroids must not be given here – they can turn a small ulcer into extensive damage.
In stromal or endothelial herpes the situation is the opposite: the damage is caused by inflammation, so steroid drops are an essential part of treatment – always together with antiviral cover, at a dose tapered gradually over weeks, and with close follow-up. This is exactly why treatment of herpes must be decided at an examination and not on your own initiative: the same drop that saves the cornea in one form of the disease harms it in another.
Preventing attacks. In people who have recurrent attacks, particularly of the stromal form, long-term preventive treatment with low-dose antiviral tablets has been shown in a large study to significantly reduce the number of attacks. The decision is tailored to each person and reviewed over time.
When a scar remains. Corneal scars after repeated attacks can impair vision. Sometimes special rigid contact lenses improve it, and where the scar is deep, a corneal transplant is considered – always under preventive antiviral treatment, so that the virus does not attack the graft.
Shingles in the eye
Shingles (herpes zoster) is caused by the chickenpox virus, which stays dormant in the body from childhood and reactivates, usually at an older age or when the immune system is weakened. When it reactivates in the branch of the nerve that supplies the forehead, upper eyelid and nose, this is shingles of the eye (Herpes Zoster Ophthalmicus). A rash that reaches the tip of the nose is a sign that the eye is also at increased risk.
Shingles can cause inflammation of the cornea and the uvea and a rise in eye pressure, sometimes weeks or even months after the rash has cleared. Therefore:
- Start antiviral tablets as early as possible, preferably in the first days of the rash.
- See an ophthalmologist even if the eye feels normal, and continue with follow-up.
- The shingles vaccine reduces the risk of the disease and its complications – it is worth asking your family doctor whether it is suitable for you.
When to have your eye examined
A red, painful eye on one side, sensitivity to light, blurred vision, blisters around the eye, or shingles on the forehead and nose – all call for an examination by an ophthalmologist as soon as possible. Anyone who has had eye herpes and feels the same symptoms again should be examined early rather than wait. Prof. Michael Mimouni is a cornea specialist; at the examination we will diagnose the exact form of the disease, tailor the treatment, and build a plan to prevent attacks and restore vision if it has been affected. Contact us to book an examination. For other eye conditions, see eye diseases. When and why to see a doctor who specialises in the cornea is explained in cornea specialist.
The information on this page is general and is not a substitute for a personal examination and medical advice. Diagnosis and treatment decisions are made only after a full eye examination. Do not use steroid drops without instructions from an ophthalmologist.
Frequently asked questions
Is eye herpes contagious?
The virus spreads through direct contact, and most people were already exposed to it in childhood. An attack in the eye is usually a reactivation of a virus already in the body, not a new infection. Even so, during an active attack it is sensible to wash your hands, avoid touching the eye and not share towels.
Why must steroid drops never be used without a doctor?
In herpes affecting the surface layer of the cornea, steroid drops without antiviral treatment can make the infection much worse and cause permanent damage. In deeper forms of the disease steroids are actually necessary – but only after a diagnosis, under antiviral cover and with follow-up by an ophthalmologist.
Can recurrent attacks be prevented?
In people who have recurrent attacks, long-term preventive treatment with low-dose antiviral tablets significantly reduces the number of attacks. The decision whether to give such treatment, and for how long, is made with the ophthalmologist, based on how often the attacks occur and how severe they are.
I have shingles on my forehead. Is my eye at risk?
Possibly. Shingles in the branch of the nerve that supplies the forehead and the eye can damage the eye, especially when the rash reaches the tip of the nose. Any shingles in this area calls for early antiviral treatment and an examination by an ophthalmologist, even if the eye itself feels fine.
